Date: Wed, 23 Jul 1997 23:24:32 -0400 From: Randall Hopper <rhh@ct.picker.com> To: Luigi Rizzo <luigi@labinfo.iet.unipi.it> Cc: freebsd-multimedia@FreeBSD.ORG Subject: Re: dma handling in the sound driver Message-ID: <19970723232432.47587@ct.picker.com> In-Reply-To: <199707240210.EAA25526@labinfo.iet.unipi.it>; from Luigi Rizzo on Thu, Jul 24, 1997 at 04:10:36AM %2B0200 References: <19970723220732.54270@ct.picker.com> <199707240210.EAA25526@labinfo.iet.unipi.it>
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Luigi Rizzo:
|Knowing which ioctl's are used by apps (commercial and not) would
|certainly help to prioritize the work on some rather than others.
Ok. Well, the only commercial app I have this info for is the MpegTV's
Linux mtv, since I buzzed it out when debugging the no-audio problem
(before dumping it for the FreeBSD version). Here's the /dev/dsp ioctls it
uses:
SETUP: DSP_SETFMT
PCM_WRITE_CHANNELS
PCM_WRITE_RATE
DSP_SETFMT
DSP_STEREO
DSP_SETFRAGMENT (requests 127 buffers, each 1024 bytes each)
(driver keeps 1024 buffer size, but adjusts
requested number of buffers down to 64 since
64k is all the mem that's available)
...
MAIN PLAY LOOP:
DSP_GETOSPACE - reflects free space across 64 bufs, each 1024bytes
write() - if space
ON MUTE OR EXIT:
DSP_RESET
Randall
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